Serena Williams' return to Wimbledon ends with dramatic defeat against Harmony Tan - CNN

Williams, watched on by her family in the stands, lost a tight first set before leveling the match in the second on Centre Court, the site of seven of her 23 grand slam singles titles.

She was a break up in the third, but Tan showed her resilience by fighting back to take a thrilling final set in a nail-biting tie break.

Asked if it was the final Wimbledon match of her decorated career, Williams said that was a question she "can't answer."

"Who knows where I'll pop up?" she added.

Williams played her first competitive matches for close to a year at Eastbourne last week, partnering with Ons Jabeur in the doubles event.

41 broke in the fourth, only for Nadal to save his best until last and seal the win with a double break.

Swiatek, meanwhile, dominated the first set against Fett in her first match since the French Open, but had to overcome a tough period in the second when Fett came close to securing a double break.